FOXBOROUGH, Mass. -- When New England Patriots safety and captain Duron Harmon stepped up to the interview podium Wednesday, he was wearing a Super Bowl LI sweatshirt, a reminder of what the team had accomplished last season. They are the defending champions.

But in a sense, they really aren’t, because there are 21 players who were on the roster for Super Bowl LI who are now elsewhere.

Such turnover is the norm across the NFL.

“Just being here, you kind of get so used to it. I mean, there’s turnover on every team each and every year,” said Harmon, who joined the team as a third-round draft choice out of Rutgers in 2013. “Each year is so different. It’s different guys, different relationships. Each year is its own year and that’s what we just try to look at.”

As the Patriots prepare for Saturday’s divisional-round game against the Tennessee Titans (8:15 p.m. ET, CBS), the changes reinforce what coach Bill Belichick often says: Anything that happened in the past has little to no relevance on the outcome of the game. He also stresses to players that it’s a “one-game season” and that it is more about playoff execution than playoff experience.

Along those lines, consider some of the changes from the roster for Super Bowl LI.

Ryan, of course, will be on the opposite sideline Saturday night after signing a three-year, $30 million deal with the Titans in the offseason.

In his place is one of the 20 newcomers to the team, six-year veteran Stephon Gilmore, who is making his first playoff appearance. Tight end Rob Gronkowski, who was on injured reserve when the Patriots won Super Bowl LI, is the 21st different player on the active roster this season.

So while the Patriots have had an impressive run of playoff success under Belichick -- they are 25-9 with five Super Bowl championships -- each season has been about a one-third turnover. That's a credit to the coaching staff, and players, for the sustained success despite all that change.

“We don’t try to say ‘We’re defending this’ because it’s completely different and it’s different guys in different roles,” Harmon said. “We just try to take one year at a time, get better each and every week, each and every day, and try to see where it takes us.”